1. Field of the Invention
The present invention relates to a wireless communication system and a wireless communication method for switching wireless channels on the basis of the switching destination information of a wireless channel.
2. Description of the Related Art
In recent years, a wireless communication system for performing the transmission and reception of a large quantity of data of a moving image, a still image, a sound, and the like between a relaying apparatus and a wireless terminal apparatus by the use of a wireless local area network (LAN) has been becoming widely used. However, because a large quantity of data is transmitted and received by wireless in such a wireless communication system, it is known that the throughput of the system lowers owing to various interference factors and the turbulence and intermittence of an image and a sound are brought out.
Accordingly, wireless communication systems are required to select wireless channels through which no communication signals interfere with each other among a plurality of wireless channels and to use the selected wireless channels in order to avoid interference. Because it is difficult for a user to perform the selection of a wireless channel according to the ambient environment, there is the technique of making a relaying apparatus judge the communication situation of each of the wireless channels to perform the switching of a wireless channel.
Japanese Patent Application Laid-Open Publication No. 2006-94394 discloses the wireless communication apparatus that transmits a switching instruction of a wireless channel to the other wireless communication apparatus preferentially than other data signals at the time of detecting the deterioration of the communication situation of the wireless channel through which wireless communication is performed. However, if a relaying apparatus changes the wireless channel when the communication situation has abruptly deteriorated or when the communication situation only in the neighborhood on the side of the wireless terminal apparatus has deteriorated, then the wireless terminal apparatus cannot obtain the information of the changed wireless channel by this technique, and it becomes impossible for the wireless terminal apparatus to perform the communication with the relaying apparatus. Accordingly, the wireless terminal apparatus must perform the scanning of all the channels to find out the changed wireless channel.
Moreover, Japanese Patent Application Laid-Open Publication No. 2008-148254 discloses the technique of obtaining the residual quantity of empty slots in an operating channel, storing the information or the like indicating a time until the change of the channel (number of super frames) and the channel after the change into a beacon signal when the obtained residual quantity of the empty slots is equal to or less than the residual quantity of the channel changing slot and when there is an empty channel, transmitting the beacon signal, and changing the operating channel to the empty channel. However, the information or the like indicating the time until the change of the channel and the channel after the change is stored in the beacon signal to be transmitted, after the determination of the change of the channel by this technique. Consequently, when a communication situation has abruptly deteriorated, the wireless terminal apparatus cannot receive the beacon signal, and the technique has the problem of the impossibility of the rapid and stable execution of the change of a wireless channel.